This invention relates generally to artificial hands and, more particularly, to an artificial dexterous hand having one or more articulated digits that can be versatilely configured so as to more easily adapt to differently shaped objects.
A variety of artificial hands are known and have widespread applications in many diverse fields, such as prosthetics, space or undersea exploration and the like. Industrial applications for artificial hands also abound. The existence of these and other applications has created an increasing need for artificial hands to reliably perform many complex or delicate tasks, particularly in certain work environments that may be innately unsuitable for task completion with the aid of an artificial hand. This need has in turn give rise to an accompanying need for artificial hands which are capable of assuming more configurations and more versatilely adapting to various work environments and to various shapes of objects.
For the purpose of allowing artificial hands to assume various configurations, artificial hands typically have articulated digits. Each digit commonly has a number of phalanges which are usually separate mechanical linkages. Each successive two phalanges are in turn interconnected by one of a series of joints which permit the phalanges to pivot or pitch relative to each other. Some joints have a series of gears for accomplishing relative pivoting or pitching of two successive phalanges. Still other joints may have pulleys which are each interconnected by a tendon or wire that is received by each pulley. In this case, the application of tensile force to the tendon causes each pulley to rotate and, thereby, pivot or pitch the phalanges relative to each other.
These known construction of joints, tend, however, to have fundamental disadvantages. A gear construction for the joints may result in an unduly heavy digit which can require a rather expensive assemblage of actuation mechanisms for operation of the hand. A gear construction can also create an artificial hand which is overly rigid or jaw-like in its movements. On the other hand, the aforementioned pulley and tendon construction may result in a digit which is too flexible and tends to easily become unstable. Moreover, both types of constructions tend to cause the phalanges of the digit to pivot arbitrarily, unless their pivoting is controlled by a complex and costly assemblage of actuation and control mechanisms associated with each joint.
Further, the digits of certain existing hands tend to be unstable during pivoting and to inadequately compensate for the effects of forces that develop near the outer or fingertip joint during the grasping or manipulation of an object by the hand. That is, the outer joints of a digit tends to experience greater forces than the other joints of the digit. These forces tends to undesirably propagate from the outer joint to the other joints such that the finger becomes unstable and may be unable to retain its desired configuration. Some efforts to address this problem employ separate motors to attempt to control the pivoting at each joint. This is, however, costly and requires a cumbersome assemblage of actuation mechanisms and complex control systems.
The nature of certain tasks and the inherent characteristics of certain work environments also require the digits of the hand to perform complex or delicate tasks without undue delay. Existing digits tend to be unable to suitably conform their pivoting or pitching configurations in a relatively short period of time. Moreover, existing digits also tend to be unable to versatilely alternate between robust and delicate modes of grasping and manipulation without expensive control mechanisms.
It should, therefore, be appreciated that there has existed a definite need for an artificial dexterous hand having one or more digits that are better capable of versatilely adapting their respective configurations to conform to various shapes of objects and which are constructed in a manner more conducive to digit stability and efficient control of the sequence of pivoting of the phalanges corresponding to each digit.